nor/flash/stm32f1x: add stm32f07x support

Added configuration to work with stm32f07x.
Tested on stm32f072discovery with libopencm3 stm32f0 blink example.

Change-Id: I63cdc9bf1f28f5951d6b4faac871cfde331c9c78
Signed-off-by: Kuldeep Singh Dhaka <kuldeepdhaka9@gmail.com>
Reviewed-on: http://openocd.zylin.com/1921


Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>